Color blind persons are often unable to reliably distinguish between various colors. Persons whose color vision is impaired include, for example, those who confuse reds and greens (e.g., either protanopia: having red cones that are not fully functional; or deuteranopia: having green cones that are not fully functional). Even people with full color vision can, at times, have difficulty distinguishing between colors. As a person ages, clouding of the lenses of the person's eyes tends to occur due, for example, to cataracts. As individuals age, they often experience changes in their ability to sense colors. Some individuals may see objects as if they have been viewed through yellowish filters. Additionally, over time, ultraviolet rays degenerate proteins in the eye, and light having short wavelengths is absorbed and blue cone sensitivity is thereby reduced. As a result, the appearance of all colors changes. Similarly, even an individual with “normal” vision can perceive colors differently when they are at an altitude that is greater than they are normally used to, or under certain medications.
To overcome the inability to distinguish colors, individuals may become adept at identifying and learning reliable cues that indicate the color of an object, such as by knowing that a stop sign is red or that a banana is typically yellow. However, absent these cues, the effect of being color blind is that they are often unable to reliably distinguish colors of various objects and images, including in cases where the color provides information that is important or even critical to an accurate interpretation of the object or image. Common examples of such objects and images include lighted and non-lighted traffic signals, and pie charts/graphs of financial information and maps. Moreover, with the proliferation of color computer displays and mobile devices, more and more information is being delivered electronically and visually and usually with color coded information.